Blooms of Single Bacterial Species in a Coastal Lagoon of the Southwestern Atlantic Ocean

Abstract

We investigated seasonal differences in community structure and activity (leucine incorporation) of the planktonic bacterial assemblage in the freshwater and brackish-water zones of a shallow coastal lagoon of the southwestern Atlantic Ocean. Alphaproteobacteria formed the dominant microbial group in both zones throughout the sampling period. After an intrusion of marine water, members of the SAR11 lineage became abundant in the brackish-water zone. These bacteria were apparently distributed over the lagoon during the following months until they constituted almost 30% of all prokaryotic cells at both sampling sites. At the first sampling date (March 2003) a single alphaproteobacterial species unrelated to SAR11, Sphingomonas echinoides, dominated the microbial assemblages in both zones of the lagoon concomitantly with a bloom of filamentous cyanobacteria. Pronounced maxima of leucine incorporation were observed once in each zone of the lagoon. In the freshwater zone, this highly active microbial assemblage was a mix of the typical bacteria lineages expected in aquatic systems. By contrast, a single bacterial genotype with >99% similarity to the facultative pathogen gammaproteobacterial species Stenotrophomonas maltophilia formed >90% of the bacterial assemblage (>10 7 cell ml ؊1 ) in the brackish-water zone at the time point of highest bacterial leucine incorporation. Moreover, these bacteria were equally dominant, albeit less active, in the freshwater zone. Thus, the pelagic zone of the studied lagoon harbored repeated short-term blooms of single bacterial species. This finding may have consequences for environmental protection.

Reproducibility of Vibrionaceae population structure in coastal bacterioplankton

“…On the other hand, a considerable fraction of populations was at low frequency or undetectable in one of the samples. This may indicate that these populations occasionally bloom, but are otherwise rare as has been shown for other bacterioplankton populations, which can experience population expansions on relatively short timescales (Rehnstam et al, 1993;Rieman et al, 2000;Piccini et al, 2006;Gilbert et al, 2012). Such blooms of specific populations while the remainder of the community remains constant are likely triggered by specific physical, chemical and/or biotic conditions and are thus consistent with finescale structuring and predictable association with what we here term 'habitats' (that is, combinations of specific parameters).…”

The pathogenBatrachochytrium dendrobatidisdisturbs the frog skin microbiome during a natural epidemic and experimental infection

“…Our finding that the abundance of Pseudomonas species declined sharply with Bd infection suggests that in the R. sierrae system, the sensitivity of Pseudomonas species to disturbance by Bd may render these bacteria ineffective at providing protection against Bd infection, regardless of whether they produce anti-Bd metabolites. Stenotrophomonas species are broadly present in the environment, including freshwater habitats, sewage, plankton samples, and soil (60); are also known to cause nosocomial infections in human patients; and have been found to be resistant to broad-spectrum antibiotics (61). Stenotrophomonas species have been isolated from amphibian skin (39,59), and an isolate from harlequin toads (Atelopus elegans) inhibited Bd growth in laboratory tests (59).…”

Towards a Latin American and Caribbean international census of marine microbes (LACar ? ICoMM): overview and discussion on some current research directions

“…Microbial diversity: Fluorescent In Situ Hybridization (FISH) and fluorescence in situ hybridization with horseradish peroxidaselabeled probes and catalyzed reporter deposition (CARD-FISH ; Pernthaler et al 2004) is used to characterize the main groups of bacteria (Prokarya and Archaea) in Uruguay coastal lagoons, the counts being performed on filters by epifluorescence counts (Piccini et al, 2006). The detailed protocols for bacterial DNA collection, filtration and extraction at the MORIO (Brazil) are described by Vieira et al (2007 a, b).…”

“…More particularly, the enormous fluidized mud deposits that occur along thousands of kilometers of the Guianas tropical continental margin downdrift of the Amazon River, are being characterized for their microbial diversity and metabolisms (Madrid et al 2001;Chistoserdov et al unpubl.). In littoral subtropical lagoons, showing important gradients, the characterization of bacterial diversity patterns is in process by means of molecular determination, as it is the case in the marine littoral area (coastal lagoons) of Uruguay (Piccini et al 2006;Alonso et al unpubl.). Adjacent waters of a strong and wide salinity gradient (Rio de la Plata and Argentinian shelf) are currently sampled in order to study the general diversity of picoplankton by comparing polluted an unpolluted systems (Costagliola et al unpubl.).…”